New finds from an open-air archaeological site in the Loiyangalani River Valley (Serengeti National Park. Tanzania) have intriguing implications for the evolution of modern human behavior, including further indications that symbolic thinking developed in humans earlier than the currently accepted date of about 35,000 years ago.

Archaeologists studying the site say it may contain some of the strongest evidence yet for the early development of modern cultural behavior in humans, and is the first such discovery of its kind in East Africa, indicating that cultural modernity may have been widespread across Africa during the Middle Stone Age.

The researchers report that preliminary excavation has yielded ochre pencils, bone artifacts, fish bones, mammal bones and two ostrich egg shell beads in association with an assembly of Middle Stone Age tools. There are other ostrich eggshell fragments that may represent debris from bead manufacture. The Middle Stone Age in East Africa originates as early as 280,000 years ago, and is replaced by the Later Stone Age at about 45,000 years ago, though none of the Loiyangalani finds have been precisely dated as of yet using advanced dating techniques.

Until relatively recently, it was generally believed that human 'behavioral modernity' -- the ability to think abstractly and to create culture and art -- developed in humans significantly after Homo sapiens evolved to its present physical form (circa 120,000 years before present) and first in Eurasia, where human art and sophisticated artifacts begin appearing about 35,000 years ago. Recent evidence, including important discoveries of sophisticated bone tools from Blombos Cave in South Africa dated at more than 70,000 years old, have weakened this argument, showing that human tool technologies were significantly advanced before humans left Africa. The decorations on two ochre pieces from Blombos Cave have been interpreted as signs of symbolic activity, but that interpretation is debated.

The researchers see the beads as significant indicators of human cultural modernity because beads are clearly decorative, and decoration strongly implies abstract and symbolic thinking. Ostrich egg shell beads may also be indicators of even broader cultural developments. While there is no evidence of how the beads were used, ethnographic studies of recent African hunter-gatherer societies show that modern beads of this type are often used in trade between groups. The methods that are used to produce ostrich shell beads are also significantly more sophisticated than any techniques used to produce the tools generally found in the Middle Stone Age. The beads, which are still produced by African Khoi-San (Bushman) cultures today, are typically produced by breaking the shell into small pieces, which are then drilled and strung on a fiber or sinew. The strung shell fragments' edges are then smoothed and rounded as a group to produce uniform beads. >from *East African Artifacts Support Evolution of Symbolic Thinking in Middle Stone Age*. March 31, 2004

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> ishango, the bone that began the space odyssey: were african women our first mathematicians?. march 8, 2002
> abstract engravings from stone age: cognitive modernity first evolved in africa. january 18, 2002
> technology and evolution: paleolithic technology and human evolution . march 13, 2001

imago
> african incubation of symbolic thought